GB2047014A - Interconnector - Google Patents

Abstract

A press-contact type interconnector, which is used for electrically connecting two electronic circuit units by sandwiching therebetween comprises an elongated contacting member having portions conductive in the transverse direction and isolated from each other in the longitudinal direction, similar to conventional press-contacting interconnectors, and an insulating supporting member 2 bonded to the elongated contacting member and extending perpendicularly to the longitudinal direction of the elongated contacting member. By virtue of the supporting member, the interconnector is handled with ease and placed with stability on a circuit unit even when the dimensions of the contacting member are extremely small. <IMAGE>

Description

SPECIFICATION Interconnectors The present invention relates to press-contact type interconnectors. With such interconnectors, it is desirable that reliable electric connection is obtained between two circuit units even with relatively low press-contacting load.

Recently, press-contact type interconnectors have found wide applications in various kinds of electronic instruments such as pocketable electronic calculators, electronic watches and the like for obtaining electric connection between two circuit units, such as between a liquid crystal display unit and a printed circuit board bearing the electronic circuit for driving the display unit. These press-contact type interconnectors are shaped in a form of an elongated piece having anisotropic electroconductivity in the direction substantially perpendicular to the length of the elongated piece.Accordingly, when the interconnector is sandwiched between two circuit units with pressure in contact with two sets of the contacting terminals on the oppositely positioned circuit units, electric connection is obtained between the contacting terminals on the different circuit units through the interconnector.

A typical example of such an interconnector piece is described, for example, in U. S. Patent 3,998,513.

The interconnector disclosed there has a structure of alternate stratification of a plurality of layers made of an electroconductive rubbery material and a plurality of layers made of an electrically insulating rubbery material integrally bonded together to give a zebra-like appearance. A variety of press-contact type interconnectors have been proposed utilizing different principles of electric conduction but all of them are equivalent in that they are in a form of an elongated piece having electroconductivity in the transverse direction but no conductivity in the longitudinal direction (see, for example, U. S. Patents 3,795,037, 3,998,512, and 3,985,413).

With the trend in the electronics industry toward more and more miniaturized designs of electronic instruments, the press-contact type intercon nectors are also required to be smaller and smaller in size not only in length but also in width and height. One of the problems in such a tiny press-contact type interconnector made, for example, of a rubbery material is that it is so soft and pliant that difficulties are encountered in handling and positioning it in the correct position between two circuit units to be connected therewith in assembling an electronic instrument.

In addition, there is a demand for a press-contact type interconnector having more and more decreased width so as that the press-contacting load per unit area of the contacting surface of the interconnector can be increased resulting in higher reliability in the electric connection between the interconnector and the contacting terminals of the circuit unit. When the width of a press-contact type interconnector is excessively small in comparison with the height thereof, the interconnector can no longer stand upright with stability between two circuit units so that there is a lower limit to the width of a press-contact type interconnector notwithstanding the eager demand for decreased widths, the height of the interconnector being determined by the dimensions a and configurations of the circuit units.

Ways were therefore sought of providing a novel and improved press-contact type interconnector capable of being handled conveniently and positioned at the correct position between two circuit units easily and with which very reliable electric connection is obtained even when the width of the interconnector is considerably smaller than the height thereof.

The press-contact type interconnector of the invention comprises (a) an anisotropically electroconductive elongated contacting member having electroconductivity within the plane substantially perpendicular to the length of the elongated member but being electrically insulating in the longitudinal direction thereof, and (b) at least one supporting member bonded to the elongated contacting member extending substantially perpendicularly to the longitudinal direction of the elongated member and made of an electrically insulating material.

The above defined structure of the inventive interconnector is particularly useful when the elongated contacting member contributing to the anisotropic electric conduction is made of a rubbery material. It is preferable that the supporting member bonded to the elongated contacting member has a width to cover the whole length of the elongated member and is in a form something like a wing.

The press-contact type interconnectors are thus easy to handle and can be placed accurately and easily at the correct position between two circuit units to be electrically connected therewith even when the width thereof is extremely small in comparison with the height thereof. Moreover, the electric connection obtained with the interconnector is reliable because the contacting member may be of a width which is not feasible in conventional interconnectors and, despite the small width of the contacting member, irregular deformation of the contacting member can be avoided by virtue of the supporting member contributing to the rigidity of the contacting member.

Embodiments of the invention will now be described with reference to the drawings in which: Figure 1 is a perspective view of a conventional interconnector.

Figure 2 is a perspective view of a basic embodiment of an interconnector of the invention.

Figure 3 is a cross sectional view of the interconnector shown in Figure 2 as sectioned and viewed along the line Ill-Ill in Figure 2.

Figure 4 is a schematic illustration of the interconnector of Figure 3 as placed on a printed circuit board.

Figure 5, Figure 6 and Figure 7 (at to Figure 7(h) are perspective view of different variations of interconnectors of the invention.

Figure 8 is a schematic illustration of the manner in which interconnector having an arrowhead-like cross section is held between two printed circuit boards.

Figure 9 and Figure 10 are perspective views of dual line interconnectors according to the invention.

Figure 1 is a perspective view ofa typical embodiment of conventional press-contact type interconnectors. The interconnector 1 is formed of an alternate stratification of the layers 1a of an electroconductive rubbery material (black portions) and layers 1 b of an electrically insulating rubbery material (white portions) and has a rectangular cross section with a width Wand a height H. Accordingly, the interconnector 1 as a whole has electroconductivity within the plane perpendicular to the length but is electrically insulating in the longitudinal direction.

The interconnector may have a cross section different from the rectangular form shown in Figure 1 according to need. Also, the interconnector may be imparted with anisotropic electroconductivity only in a surface layer covering an insulating core. Such an interconnector can be prepared by printing on the surface of an elongated member of an insulating rubber to give a striped pattern with an electroconductive ink or by adhesively bonding a sheet member on which a striped pattern has been printed with an electroconductive ink around an insulating core.

When the width W of the interconnector 1 is considerably smaller than the height H, the interconnector 1 can no longer be placed with stability between two circuit units to be electrically connected therewith, not to mention the difficulties in handling and positioning it in the correct position between the circuit units due to its excessive flexibility and pliability.

Figure 2 is a perspective view of a basic embodiment of press-contact type interconnector of the invention and Figure 3 illustrates a cross sectional view of the interconnector shown in Figure 2 as sectioned along the line Ill-Ill in Figure 2, in which the elongated contacting member 1 is constructed as an alternate stratification of the conductive layers 1a and insulating layers 1 b as in the conventional ones shown in Figure 1 and is provided with a supporting member 2 made of an insulating material and bonded to the contacting member 1 and extending substantially perpendicularly to the longitudinal direction of the elongated contacting member 1.

Figure 4 illustrates the same interconnector as is shown sectioned in Figures 2 and 3 as placed on a printed circuit board 13 having contacting terminals 14. Without the supporting member 2, the contacting member 1 could no longer stand on the printed circuit board 13 with stability whereas, in the interconnector as shown, the supporting member 2 prevents the contacting member 1 from falling over so that efficiency of assembly of the electronic instrument by use of the interconnector is greatly enhanced.

In this connection, the supporting member 2 must have a rigidity and length sufficient to effectively support the contacting member 1 when the interconnector is put on a circuit unit or, typically, on a flat surface. In so far as the above requirements are satisfied, a wide variety of the materials and dimensions or configurations of the supporting member 2 can be used. For example, the supporting member 2 may be in a form of a simple rod although the embodiment shown in Figure 2 has a supporting member 2 in a form of something like a wing of an airplane.

The contacting member 1 and the supporting member 2 may be bonded tog-ether by use of a suitable adhesive agent or may be integrally molded, if possible. In particular, the embodiment shown in Figure 2 cannot be prepared by integral molding and it is recommended in such a case that a hole or mortise is provided in the contacting member 1 and the end of the supporting member 2 is inserted into the mortise, if necessary, with application of an adhesive agent to form a mortise-andtenon joint.

Figure 5 illustrates a modification of the embodiment shown in Figure 2, in which the width of the supporting member 2 is increased so as to extend over whole length of the contacting member 1. This embodiment is particularly advantageous when larger rigidity is to be imparted to the contacting member 1 with consequently increased standing stability of the interconnector on a circuit unit. An additional advantage is obtained with this configuration of the interconnector in that the supporting member 2 serves as a heat radiator for the heat produced in the contacting member 1 owing to the increased radiant surface area, especially, when the inerconnector is used for connecting two circuits involving relatively large electric currents.When such an advantage is desired, it is recommended thatthe supporting member2 is made of a material having a thermal conductivity as large as possible in so far as the necessary mechanical and electrical properties are not unduly impaired.

The embodiment illustrated by Figure 6 resembles the embodiment in Figure 5 in overall appearance but is quite different in structure. Thus, the contacting member and the supporting member in this case are not fabricated separately to be bonded together subsequently. Instead, the member 12 having a T-shaped cross section is fabricated of an insulating material by extrusion molding or other suitable methods to serve as an integral combination of the supporting member 1 2b and the core portion of the contacting member 12a, around which is adhesively bonded a sheet member 3 which has been provided with a striped pattern with an electroconductive ink to form electroconductive striped zones 3a leaving insulating zones 3b therebetween. Interconnectors of this type are particularly suitable for mass production since the elongated member 12 can be first fabricated in a continuous length by extrusion molding and the sheet member 3 which is also a continuous length with printed electroconductive stripes 3a thereon is adhesively bonded around the core portion 12a ofthe elongated member 12to give a continuous length interconnector which is subsequently cut into the individual product lengths.

In the above described embodiments of the press contact type interconnectors of the invention, it is assumed that the contacting member 1 has a rectangular cross section and the supporting member 2 is in a form of a plate of uniform thickness. It is of course optional that the contacting member 1 has different cross sections and the supporting member 2 has a non-uniform thickness. For example, it is advantageous that the width of the contacting member 1 is small in the portions coming into contact with the contacting terminals on the circuit units to be electrically connected therewith. Severai of such modifications are shown schematically in Figure 7 (a) to Figure 7 (h). These figures are self-explanatory and need not be explained.

Figure 8 illustrates the manner in which an interconnector having a cross section like an arrowhead is held between two printed circuit boards 13, 13 in contact with the contacting terminals 14, 14 at the edges of the contacting member 1.

Figure 9 is a perspective view of a dual line interconnector in which a single frame-like supporting member 8 is shared by two contacting members 1, 1. Figure 10 is a perspective view of another dual line interconnector which is obtained by tail-to-tail bonding of two interconnectors as shown in Figure 7 (c).

Claims (6)

1. A press-contact type interconnector which comprises (a) an anisotropically electroconductive elongated contacting member having electroconductivity within the plane substantially perpendicular to the length of the elongated member but being electrically insulating in the longitudinal direction thereof, and (b) at least one supporting member bonded to the elongated contacting member extending substantially perpendicularly to the longitudinal direction of the elongated contacting member and made of an electrically insulating material.

2. A press-contact type interconnector as claimed in claim 1 wherein the supporting member has a rigidity and length sufficient to prevent the interconnector from falling over when the interconnector is placed on a flat surface.

3. A press-contact type interconnector as claimed in claim 1 or 2 wherein the supporting member has a width extending substantially over whole length of the elongated contacting member.

4. A press-contact type interconnector as claimed in claim 3 wherein the width of the contacting member is narrowed at the longitudinal peripheries so as that the elongated contacting member has edge lines parallel to the supporting member.

5. A press-contact interconnector substantially as described with reference to Figures 2-10 of the drawings.

6. An electronic instrument comprising an interconnector as claimed in any preceding claim.